Method of manufacturing and assembling ball-bearings.



No. 881,471. PATENTED MAR. 10, 1908.

E. G. HOFFMANN.

METHOD OF MANUFACTURING AND ASSEMBLING BALL BEARINGS.

APPLICATION FILED JUNE 13.1907.

3 SHEETS-SHEET l.

W MW 25 Y' PATBNTED MAR. 10/1908. B. G. HOPFMANN. METHOD OF MANUF AGTURING AND ASSEMBLING BALL BEARINGS.

APPLICATION FILED'JUNE 1a. 1901.

8 SHEETS-SHEET 2.

A TOHNEYS No. 881,471. PATENTED MAR. 10, 1908. Y

E. G. HOFFMANN.

METHOD OF MANUFACTURING AND ASSEMBLING BALL BEARINGS.

APPLICATION FILED JUNE 13,1907.

3 SHEETS-SHEET 3.

INVENTOR AT ORA E78 UNITED TE ERNST GUSTAV HOFFMANN, OF NEW ROCHELLE, NEW YORK.

METHOD OF MANUFACTURING. AND ASSEMBLING BALL-BEARINGS.

Specification of Letters Patent.

Yatented March 10, 1908.

Application filed June 18, 1907. Serial No. 878,699.

To all whom it may concern:

Be it known that I, ERNST GUSTAV Horr- MANN, a citizen of the United States, residing in the city of New Rochelle, in the county of VVOStCiiOStGl, in the State of New York, have invented certain new and useful Improvements in Methods of Manufacturing and Assembling Ball-Bearings, of which the following is a specification, reference being had to the accompanying drawings, forming a part hereof.

The desirability of providing, in ball or roller bearings, uninterrupted race ways, that is, race ways which have no break in their continuit such as would be caused by a slot or note whether filled by a filling iece or not, or any line of separation, has ong been recognized and various attempts have been made to meet the demand for such a bearing.

It has been proposed, for example, to provide uninterrupted and integral grooved race ways and by displacing them eccentrically in the same plane to form a crescent shaped opening in which a limited number of the balls can be introduced, the balls subsequently being distributed uniformly and held a art by separator or s acing devices, but; t e limited number of he s which can thus be introduced causes the bearings which are so roduced to fall far short of the ideal bearing. t has also been proposed to provide uninterrupted and integral grooved race ways and, 'after placing one within the other but with the axes oblique, to force the race ways and balls into the same plane in a suitable ress, but this procedure invariably mutiate s the raceways and distorts the balls more or less, so that the bearing produced is im erfect.

y the present invention it has been sought to produce a ball or roller bearing with uninterrupted and integral grooved race ways and with the full number of balls or rollers, that is the maximum number which can be lodged in the available space,

and without any mutilation, permanent distortion or other injury to any of the members of the bearing.

In accordance with the invention the outer race way is rapidly expanded by the application of such an electric current as is eniployed in electric welding while the temper of the working surface is practically unaffected by heat, and at the instant of maxi-'55 mum expansion the two race ways and the balls or rollers are 'moved into the same plane. The outer race way is immediately cooled and by its contraction the balls or rollers are embraced between the walls of the grooves of the two race ways. In this manner neither the inner race way nor the balls are heated appreciably and, if the operation is properly conducted, the working surface of the outer race way is not sufliciently heated to affect its temper or finish. Moreover, being uniformly heated by the electric current, the outer race way suffers no permanent distortion. If the depth of the grooves with relation to the size of the balls and the dimensions of the race ways is pro erly predetermined, the accuracy or fit of t e several members of the completed bearing leaves nothing to be desired.

The invention will be more fully explained hereinafter with reference to the accompanying drawings in which is illustrated apparatus suitable for the practice of the invention, and in which Figure 1 is a view in vertical central section of an apparatus, including the members of the bearing, which is suitable for the practice of the invention, the parts being shown in the positions which they occupy just before complete assembling. Fig. 2 is a plan view of a bearing produced by the improved method. Fig. 3 is a view in section on the plane indicated by the broken line 3-3 of Fig. 2. Fig. 4 is a view similar to Fig. 3 but *Willh the ball races separated. Figs. 5 and 6 are lan views illustrating different modes of app ying the electric current for the purpose or expanding the outer race way.

In the drawings the bearing is shown as v on its outer surface a shallow groove l) of such depth as to prevent lateral displacement of the balls when the bearing is assembled;

balls 0 of the full number, that is of the maximum number capable of being lodged in the available space; and an outer, uninterrupted,

integral race way (1 having formed circumferentially, in its inner surface, a shallow roove 6, also of sufficient depth to revent lateral displacement of the balls w en the amounted between and in contact with two annular electrodes or terminals and g of a suitable electric circuit, so that in this case the current flows through the race way or ring d in a direction arallelwith the axis of the ring. Annular s 'elds h, provided if desired' with suitable acking i, are ressed against the ends of the ring (1 not on y incidentally to rotect the inner race way or ring a and the balls from heat radiated by the electrodes or terminals f and g, but mainly to protect the latter as well as the main body of the ring (1 from the action of the cooling medium which may be supplied, during the operation, through an annular nozzle is. In the apparatus shown there is also rovided an annular plunger Z.

en the parts of the-apparatus and the bearing are in the position represented in Fig. 1 the electric current is turned on and instantly the body of the race way or ring (I is heated to an extent 'suflicient to permit the balls a, surrounding the inner race way or ring a, to pass the upper shoulder or side of the groove 6 when pressed in the pro er direction by the plunger Z. The inner an outer race ways and the balls are thus brought into a common lane; The action of the electric current 111 producing the expansion of the outer ring or race way is so rapid that the temperature of the inner or working face of the cooling medium.

the ring is not raised to such a degree as to affect its temper and finish, especially if a cooling medium, such as cold water, is continuously ap lied to the inner face of the ring, as by t e nozzle 7:. The electric current is cut off at the instant that the outei ring is expanded to the desired extent and the members of the bearing are brought into the common plane and the outer ring is immediatelycooled by the continued flow of the cooling medium, contractin to its initial dimensions and causing the ba s to be embraced between the walls of the grooves in such amanner as to revent their lateral displacement. The ba s and inner rin are entirely unaffected by the heating 0 the outer ring, both byreason of the brief period of time during which the outer rin is heated and by reason of the protection a orded by Obviously the outer ring or race way (1 may be subjected in various ways to the action of the electric current. Thus, as shown in Fig. 5, the electric current ma be made to passcircumferentially th ough the ring from the one electrode or terminal f to the other electrode or terminal 9 which are brought into contact with the outer circum ferential surface of the ring. So also, as shownin Fig. 6, the electrodes f and g might be a plied to metal bands or clamps m and n w ich are in contact with the circumferentially, so that the ring itself is heated by the current which passes through it and by immediate contact with the heated bands or clamps. Obviously also, the rin or race way-may itself constitute the secon ary coil of an electric transformer so that the electric current is produced therein by induction without electrical contact with the primary circuit. Various other modes of applying the electric current will suggest themselves and it is to be understood that the invention is not restricted to the details of construction or arrangement of the apparatus which may be em loyed in the practice of the invention.

he invention, as will be readily apparent, is no less applicable to the se aration of the members of such a ball bearlng as that referred to, than to the assembling thereof. It

frequently happens that ball bearings of this character must be taken apart for correction of defects and in such a case the outer ring is expanded by the application of an electric current, as already described, and at the instant of maximum expansion the inner ring and the balls are forced out. The claims herein are therefore to be understood as covering the separation as well as the bringing together of the members of the bearings.

. I claim as my invention:

1. The method ofmanufacturing' a ball bearing which consists in forming uninterrupted, integral inner and outer rings or race 7 ways grooved respectively on the outer and inner circumferential faces to embrace the balls and prevent lateral displacement thereof when assembled, subjecting the body of the outer rin to an electric heating current while the wor 'ingface thereof and the inner ring and the bal s are maintained, at a low tern erature, moving the ring and balls relative y in the desired direction at the instant of maximum expansion to embrace or release the balls, and immediately cooling the outer ring to prevent the heating of its working face.

2. The method of manufacturing and assembling a ball bearing which consists in forming uninterrupted, integral inner and outer rings or race ways grooved respectively on the outer and inner circumferential faces to embrace the balls and prevent lateral displacement thereof when assembled, subjecting the body of the outer ring to an electric heatin current while the working face thereof an the inner ring and balls are maintained at a low temperature, movin the This specification signed and witnessed rings 'flli d balls into the same plane1 at t e idn this 12th day of June, A. D. 1907.

stant 0 maximum ex 'ansion an imme ie etely cooling the cute ring to prevent the ERNST GUSTAV HOFFMANN' 5 heating of its working face and to permit it Signed in the presence ofto contract and cause the balls to be em- H. L. PIERCE,

braced in the grooves ofth'e two rings. AMBROSE L. OSHEA. 

